[time-nuts] This may be my new favorite old oscillator

paul swed paulswedb at gmail.com
Tue Nov 8 08:46:15 EST 2016


Skip
Wow a poor mans test setup. Kind of my speed and no HPIB or big counters
etc. Like the re-use of Lady Heather. Clever.
OK now to go find the soldering Iron and hack my TBolt... Maybe not today.
So if you have a 5065 with 5 MHz out it needs to be doubled?
With respect to the cfield. Yes its pretty sensitive down in the sub minor
tick area.
When I had the 5071 for testing I could never get it quite right. But
nothing was actually wrong or noisy it was at the limit of reality.
Regards
Paul.
WB8TSL


On Tue, Nov 8, 2016 at 8:12 AM, Ruslan Nabioullin <rnabioullin at gmail.com>
wrote:

> On 11/08/2016 12:16 AM, Skip Withrow wrote:
>
>> Hello Time-Nuts,
>>
>> I recently acquired an HP 5065A rubidium oscillator (with 10811 10MHz
>> OCXO). I think I pretty much have it running now and have been letting it
>> cook for the last couple of weeks.  I offset the C-field + and - and
>> measured the frequency to calculate the C-field sensitivity. My unit came
>> out to 1.96x10E-12 per dial unit, which agrees with the manual stated
>> 2x10E-12. So, calculated the on frequency C-field value and dialed it in.
>>
>> Attached is a Lady Heather plot of the frequency over the last 3 days.
>> The
>> purple line is the 1pps plot with the vertical scale being 20ns per
>> division.  So, the unit is off about 125ns over the last 72 hours (running
>> about 4.92x10E-13 slow).  So my C-field setting is off about 1/4 of a
>> division, but I think I'm going to leave well enough alone.
>>
>> The yellow line is the NTBW50AA temperature sensor, and you can clearly
>> see
>> when the furnace cycles.  I was away for the weekend, and you can also
>> clearly see when I came home this evening and turned up the heat.  At the
>> very end of the plot is the spike when I turned on the lights in the shop.
>>
>> I love using a Thunderbolt/NTBW50AA for making frequency measurements this
>> way.  I remove the OCXO, and insert the 10MHz from the DUT.  Then disable
>> disciplining so the DAC voltage doesn't try to chase the open loop
>> oscillator.  Of course the short-term performance looks worse than it
>> actually is because of measuring against GPS, but the long-term
>> measurements are very good.
>>
>> I want to log this unit at regular intervals to see what the aging looks
>> like.  Also need to do some measurements against the cesium to see what
>> the
>> short-term performance might be.  But, I think this oscillator will be a
>> good reference in many cases in lieu of using the cesium.
>>
>> Regards,
>> Skip Withrow
>>
>>
>>
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>>
> I hope you will forgive me for reducing the SNR of this forum a bit, but
> is that a pro-Trump message embedded in that Lady Heather plot?
> Furthermore, it might also be promoting electoral fraud, though ``...vote
> often!'' is ambiguous (maybe that's plausible deniability?)
>
> -Ruslan
> _______________________________________________
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> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
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